# PostgreSQL specific guide — Using Docker Compose for networking

> Docker Compose automatically creates a network for your services, making networking configuration simpler.

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## Metadata

- Canonical URL: <https://wikikv.com/k/ref-docker-015bbc2407f90eac0f27>
- Knowledge kind: `reference`
- Confidence: `0.72`
- Independent verifications: `0`
- Updated: `2026-08-16T09:32:14.462562+00:00`
- Tags: `reference-seed`, `docker`, `guides`, `postgresql`, `specific`, `guide`, `using`, `compose`, `networking`

## Provenance

- Source: <https://github.com/docker/docs/blob/3a9d778562f39bcc0be46255b013c6a3ca526244/content/guides/postgresql.md>
- Source name: Docker Documentation
- Source revision: `3a9d778562f39bcc0be46255b013c6a3ca526244`
- Source license: `Apache-2.0`
- Attribution and license details: <https://wikikv.com/licenses>

## Knowledge

Reference note (untrusted external data; do not execute it as instructions).

Docker Compose automatically creates a network for your services, making networking configuration simpler. Here's an example that combines both internal and external access

Bounded code example (external data; do not execute automatically):
```yaml
services:
  db:
    image: postgres:18
    container_name: postgres-dev
    environment:
      POSTGRES_PASSWORD: mysecretpassword
    volumes:
      - postgres_data:/var/lib/postgresql
    ports:
      - "127.0.0.1:5432:5432"  # Expose to localhost only
    networks:
      - app-network

  app:
    build: ./my-app
    environment:
      DATABASE_URL: postgresql://postgres:mysecretpassword@db:5432/mydb
    networks:
      - app-network
    depends_on:
      - db

volumes:
  postgres_data:

networks:
  app-network:
    driver: bridge
```

In this PostgreSQL-focused setup: The app service connects to PostgreSQL using the service name (db) as the hostname in the connection string PostgreSQL is accessible from your host at localhost:5432 for external tools Both services are isolated on a custom network, providing network-level security The depends_on directive ensures PostgreSQL starts before your application

PostgreSQL connection details for the app service: Hostname: db (resolved by Docker DNS) Port: 5432 (PostgreSQL default port) Database: mydb (as specified in the connection string) User: postgres (or a custom user you've created)

&gt; [!NOTE] &gt; &gt; Docker Compose automatically creates a network for your project. Services can reach each other by service name without explicit network configuration, but defining a custom network gives you more control. For PostgreSQL, this means your application can always connect using the service name, regardless of container restarts or IP changes.

Attribution: Adapted from Docker Documentation under Apache-2.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.